Influence of Water Stress on Cold-Induced Sweetening in Leafy Vegetable, Brassica juncea L.

The occurrence of low temperature sweetening in Brussica juncen L., an apparently chilling-tolerant leafy vegetables, has been investigated in relation to the effect of water stress and postharvest age (i.e. fresh harvest vs previously stored samples). The magnitude of cold-induced sweetening in B. juncea leaves was estimated to vary from 10–145% relative to the corresponding nonchilled samples. Previously stored leaves showed greater tendency to accumulate sugars but was apparently less responsive to cold-induced sweetening than freshly harvested leaves. Water stress synergistically enhanced this low temperature sweetening response; markedly greater and/or faster accumulation of sugars occurred in leaves that were both chilled and stressed. The majority of the total sugar increase was attributable to non-reducing sugars.     

MICROBIOLOGICAL, PHYSICO-CHEMICAL AND TOXICOLOGICAL QUALITY OF TRADITIONAL TURKISH CHEESE DESSERTS

ABSTRACT

A total of 100 fresh‐cheese‐based desserts (Hosmerim and Cheese helva) from nine different production areas in Marmara Region of Turkey were studied. There were no statistically significant differences in microbiological composition between Hosmerim and Cheese helva. Mean values of APC, Staphylococcus aureus, molds, yeasts, osmophilic yeasts for Hosmerim were 5.7 × 10⁴, 8.0 × 10², 1.8 × 10³, 2.8 × 10³, 1.6 × 10³ cfu/g, respectively, while coliform bacteria, Escherichia coli and Bacillus cereus were <10 cfu/g. Results for Cheese helva were slightly higher. Salmonella spp. and staphylococcal enterotoxin were not detected in 25 g of any sample. Cheese helva, however, had a significantly lower pH and significantly higher contents of protein, fat and carbohydrates, and thus, also a higher content of dry matter. Within each product category, a large variation was observed for both microbiological counts as well as for the chemical composition. This indicates a lack of standardization in the manufacturing process and prompts for the establishment of appropriate process control measures.

PRACTICAL APPLICATIONS

The aim of this study was to determine the chemical and hygienic quality traits of traditional cheese desserts, namely Cheese helva and Hosmerim. For this purpose, 50 Cheese helva and 50 Hosmerim samples obtained from different regions in Turkey were analyzed on account of their microbiological, physico‐chemical and toxicological properties. The presence of some pathogens in the samples and the variable chemical composition indicate that the production process should be defined in “Codes of Good Manufacturing Practice” and the product characteristics should be codified in order to achieve a product with a defined level of microbiological safety.     

EVALUATION OF ANTIOXIDANT ACTIVITY, PHENOLICS, SUGAR AND MINERAL CONTENTS IN DATE PALM FRUITS

Sugar and mineral compositions of 10 Tunisian date varieties were investigated. Hydrophilic (aqueous extract) and hydrophobic extracts (ethanol extract) were used to determine the phenol contents and the total antioxidant activities of these dates. Results showed that date fruit varieties were rich in soluble sugars, which varied from 35.57 (Smiti variety) to 77.88 g/100 g fresh weight (FW) (Korkobbi variety). Several minerals were also present in the following order; K, Ca, P, Mg, Na, Fe, Cu, Zn and Mn. The potassium content reached 0.74 g/100 g dry weight in Smiti variety. For all date varieties, the phenol content did not exceed 9.70 (milligram of gallic acid equivalent/100 g FW). The original antioxidant activity reached 31.86 mg of ascorbic acid equivalent antioxidant capacity/100 g (FW) for Garn ghzal variety. However, it was only 17.77 for the Nefzaoui. Therefore, it can be deduced from these results that all these fruit varieties can be considered as high-energy food and only Garn ghzal seems to be interesting for technological purposes as food antioxidants.

PRACTICAL APPLICATIONS

The date palm ( Phoenix dactylifera L.) has a very important economic, social and ecological role for the people of the arid and semiarid regions. The date world production tripled while passing from 2,289,511 tons in 1974 to 6,772,068 tons in 2004. In Tunisia, dates witnessed a remarkable development during the last years and the production reached an average of 110,000 tons per year. Unfortunately, this progress in production is accompanied by an increasing loss of secondary varieties. Among these abandoned varieties are those of Gabès oasis. In this context, our work focuses on valorizing these secondary varieties by determining their nutritional and medicinal properties.     

The biodiversity and evolution of lactic flora during ripening of the Iranian semisoft Lighvan cheese

Ninety‐five isolated strains of Lactic acid bacteria (LAB) were identified from Lighvan cheese. The LAB evolution showed the dominance of lactococci and lactobacilli in the first stage and substitution of these genera by enterococci at the end of ripening. The most predominant strains were Enterococcus faecium (22.44%), Lactococcus lactis ssp. lactis (20.4%), Lactobacillus plantarum (18.36%) and E. faecalis (14.28%), respectively. Eleven and 51 different carbohydrate fermentation profiles were observed according to API 20 STREP and API 50 CH, respectively. API 20 STREP dendogram showed identical fermentation profiles of some E. faecalis and E. faecium strains, indicating that these strains might be well adapted to the whole cheese manufacture.     

BRUISING AND SPLITTING OF APPLE FRUIT UNDER UNI-AXIAL COMPRESSION AND THE ROLE OF SKIN IN PREVENTING DAMAGE

Whole apples were compressed uni-axially with the core at right angles (horizontal compression) and parallel (vertical compression) to the direction of force. Under horizontal compression, the apple begins to bruise as soon as force is applied. The energy absorbed is proportional to the volume of bruise produced. Resistance to bruising varies with variety. In this orientation the fruit does not deform elastically, bruises easily, and the skin is not important in preventing bruising. Under vertical compression the apple is a much more elastic structure and can expand laterally. It can withstand greater deformation without damage. Rock Pippin can elastically absorb up to 0.5 J before damage. In this orientation, skin plays an important part in preventing cracking under tension. Any damage to the skin greatly reduces the structural strength of the fruit and renders it much more susceptible to cracking. Apples stacked in boxes seldom experience energies greater than 0.5 J. Storing apples in a vertical orientation can therefore reduce risk of bruising.     

The effects of incorporating wild‐type strains of Lactococcus lactis into Turkish white‐brined cheese (Beyaz peynir) on the fatty acid and volatile content

The development of free fatty acids (FFA) and volatile flavour compounds in the Turkish white‐brined cheese Beyaz peynir made by using three wild strains of Lactococcus lactis subsp. lactis was investigated over 90 days. Results showed that production of both FFA and flavour compounds in the control (PK1) and experimental cheeses (MBLL9, MBLL23 and MBL27) was strain dependent. The hydrolysis of milk fat was more evident in the cheese made using Lc. lactis subsp. lactis MBL27. Considering the production of fat breakdown compounds and acidification activities of the strains MBLL23 and MBL27, the combination of these strains could be proposed for the production of white‐brined cheese.     

INACTIVATION OF ESCHERICHIA COLI O157:H7 ON INOCULATED ALFALFA SEEDS WITH OZONATED WATER UNDER PRESSURE1

Alfalfa seeds inoculated with Escherichia coli O157:H7 (～10⁵ CFU/g) were subjected to low hydrostatic pressure. Seeds immersed in ozonated water at 4C were held at 8 and 12‐psi ozone pressure for 2, 4, 8, 16, 32, and 64 min. Alternatively, seeds were continuously sparged with ozone for up to 64 min and then held at 12 psi for 5 min. Controls consisted of sparging and pressurization with air. Thirty‐two minute treatments of continuous ozone sparging followed by pressurization of seeds at 12 psi for 5 min were repeated with the addition of four surfactants (Tween 20, Tween 80, SPAN 20, and SPAN 80) in the treatment water. Enumeration of E. coli O157:H7 on treated, untreated, and control seeds was done on tryptic soy agar supplemented with 50 μg/mL of nalidixic acid. The reduction in population of E. coli O157:H7 on seeds treated with the 8 and 12 psi hydrostatic pressure in ozonated water ranged from 0.74 ?1.56 log₁₀ CFU/g and 0.72 – 1.62 log₁₀ CFU/g, respectively. Control treatments carried out with air pressurization of seeds resulted in maximum population reductions of 1.55 log₁₀ and 1.83 log₁₀ CFU/g for 8 and 12 psi, respectively. For seeds treated with continuous ozone sparging (2 – 64 min) followed by pressurization at 12 psi for 5 min, the highest reduction was 2.03 log₁₀ CFU/g. Reductions were, however, not significantly different (P > 0.05) from control treatment (with air) which reduced the populations by 0.57 – 2.19 log₁₀ CFU/g. The presence of surfactants during continuous sparging of water followed by pressurization at 12 psi was not beneficial. None of the treatments adversely affected the germination of the seeds.     

SOLVENT EXTRACTION OF PAKISTAN COALS (III) EXTRACTION AND CHARACTERIZATION OF THE EXTRACTS BY SPECTROSCOPIC TECHNIQUES

Abstract

The Makerwal coal of Pakistan gives higher extractibi1ity with Tetrahydrofuran ( THF ) as compared to Sharigh, Sor-Range and Lakhra coals. The structural characterization of Pakistan coal extracts by FT-IR spectroscopy indicates that all the extracts contained less condensed aromatic rings in comparision to their original coal.